超高精細映像におけるマクロブロックサイズ拡張手法に関する解析的考察

抄録

Ultra-high resolution video is expected to be one of the next-generation high quality video formats. Current video coding technology H.264 achieves the maximum amount of coding efficiency from among the existing coding standards. However, even H.264 is not sufficient enough for ultra-high resolution video distribution service due to a lack of coding efficiency. Therefore, an enhanced video coding technology is strongly required to improve the coding efficiency. In the past works, several approaches for extending the macroblock (MB) size have been proposed, and these researches showed that extended MB size technology improved the coding efficiency, especially for high resolution video. However, a clear description of the performance improvement mechanism has yet to be presented. We analytically consider the coding characteristics of an extended MB size scheme for ultra-high resolution video in this paper. We clarified the coding gain mechanism of this technology based on a R-D characteristics analysis. Furthermore, we analytically confirmed that the extended MB size scheme was most effective at high-resolution and low-bitrate video coding. Finally, we conducted a coding experiment and found that the maximum bit reduction ratio reached approximately 15% using an optimal coding control for the extended MB size scheme.